To reproduce:

1. Create any Java Application Project
2. Create JPanel form
3. Add a JLabel
3. Open property sheet and select the JLabel's "foreground" property.
4. Click on "..." button to show the Color Chooser based custom editor panel 
dialog (supplied by the ColorEditor PropertyEdior).
5. Select different color (say red). The "foreground" property value cell in 
the property sheet still shows the original color. 
6. Now minimize NetBeans and restore it or in some way obscure and show 
the "foreground" property value cell in the property sheet.
7. Now the "foreground" property value cell in the property sheet shows the 
color selected in the Color Chooser based custom editor panel dialog which the 
user has not commited yet.

I think the reason for this is that the property sheet is implemented as a 
JTable and the property value cell is implemented as a cell renderer. The cell 
renderer paints itself whenever it is obscured and shown. In case of 
ColorEditor PropertyEditor the renderer delegates the painting to paintValue() 
method of PropertyEditor which has the uncommited value from Color Chooser. 
This only happens when the user somehow makes the property value cell to 
repaint and is misleading. Once the Color Chooser dialog is hidden (by click 
on Ok or Cancel button) the value in the property value cell does revert to 
the correct value.

I think the property sheet should cache the property value rather than the 
trasient value being edited. The value in the cell should be updated only when 
the user click OK. It could be considered a bug in the PropertyEditor - that 
it paints the transient value instead of property value.